So far, for example, Patent Document 1 discloses an exhaust system of an internal combustion engine which includes a so-called “Twin entry turbocharger”. In this internal combustion engine equipped with the twin entry turbocharger, it is arranged such that exhaust gas discharged from one cylinder and exhaust gas discharged from the other cylinder are separately introduced into a turbine via each scroll passage thereof. In addition, the conventional internal combustion engine includes two exhaust bypass passages, which are arranged so as to branch off from each of two scroll passages described above and be introduced into a catalyst after bypassing the turbine, as independent passages from each other.
Including the above-described document, the applicant is aware of the following documents as a related art of the present invention.    [Patent Document 1] Japanese Laid-open Utility Model Application Publication No. S63-202729    [Patent Document 2] Japanese Laid-open Patent Application Publication No. H09-125941    [Patent Document 3] Japanese Laid-open Patent Application Publication No. H11-173138